Proposed uniform nomenclature for the proteins and protein domains of the bacterial phosphoenolpyruvate: sugar phosphotransferase system

Abstract

The phosphoenolpyruvate:sugar phosphotransferase system (PTS) consists of two general energy-coupling proteins, enzyme I and HPr, as well as the sugar-specific permeases, commonly referred to as the enzyme II complex (15,19,24,26). The system catalyzes the concomitant transport and phosphorylation of its sugar substrates in a process termed group translocation (16,25). The PTS permeases found in a variety of bacteria may consist of one, two, three, or four distinct polypeptide chains and, in certain instances, some of these sugar-specific proteins are fused to protein domains which serve the general energy-coupling function(s) of enzyme I and/or HPr (8,31,34) (see Fig. 1 and 2 for schematic depictions). Evidence suggesting that the entire enzyme II complex is required for concomitant sugar transport and phosphorylation but that enzyme I and HPr merely function to phosphorylate this complex has been presented (4, 9). The enzyme II complex should therefore be considered the functional unit designated permease in this paper.Recent sequence comparison studies have shown that most of the PTS permeases are homologous, i.e., derived from a common ancestral protein (13,21,28,33). These group translocators, comprising the major group of the enzyme II complexes, generally have similar molecular weights of about 68,000, corresponding to about 635 total amino acyl residues (31). Most of them consist either of a single polypeptide chain, commonly termed enzyme II, or of two proteins, commonly called an enzyme II-III pair or an enzyme IIB-IIA pair (15,31). In a few cases, these permeases consist of three or four proteins (6,14,22 [5, 12a, 14]). These three permeases of the splinter group lack sufficient sequence similarity with the major group of PTS permeases to establish homology with them, but they are clearly homologous to each other.At the present time, well over 12 PTS permeases have been completely sequenced. While the permeases within the major group are homologous, sequence comparisons have revealed that during their evolution, the various hydrophilic and hydrophobic domains have become either fused to each other in different orders and combinations or spliced from each other to become distinct polypeptide chains (2, 13, 22, 31, 34). The various possibilities are illustrated in Fig. 1 and 2. In some cases, sequence similarities among permeases are insufficient to establish homology, either for all or for part of a particular permease complex. Regardless of whether a PTS permease consists of one, two, three, or four polypeptide chains, the entire complex must probably be present in association with the membrane to efficiently transport sugar (4,5,9). It therefore seems that the proteins which constitute a PTS permease function as an enzyme unit, the enzyme II complex, and that the number of polypeptide chains as well as the order of the domains within any one protein constituent of a PTS permease is largely immaterial to the function of that permease.At present there is no uniform nomenclature for the proteins and pr...

Cloning and Comparison of Third β-Glucoside Utilization (bglEFIA) Operon with Two Operons ofPectobacterium carotovorumsubsp.carotovorumLY34

“…PTS EII typically consists of two hydrophilic domains (EIIA and EIIB) that bind to the sugar substrate and a membrane spanning domain for transport (EIIC) 14,32,37) whereas the IIA, IIB, and IIC components can occur as individual proteins. 13,38) Currently, six families of sugarspecific PTS transporters have been identified.…”

“…Representing the sugar-specific permease, EII complexes usually possess cytoplasmic IIA and IIB and a membrane-spanning IIC. 9,14) The Pcc strain LY34 used in the present study was originally isolated from Chinese cabbage with soft-rot symptoms. To analyze their importance in phytopathogenicity, three different kinds of cellulases were previously isolated: CelA, CelB, and CelC of Pcc LY34.…”

Induction of the Bacillus subtilis ptsGHI operon by glucose is controlled by a novel antiterminator, GlcT

“…The separate domains of EII may occur as individual or multidomain proteins (Saier and Reizer, 1992).…”

Rate and Equilibrium Constants for Phosphoryltransfer between Active Site Histidines of Escherichia coli HPr and the Signal Transducing Protein IIIGlc

“…Among the diverse functions governed by the PTS is the translocation of PTS sugars across the cell membrane concomitant with their phosphorylation, and regulation of the expression of several non-PTS sugar operons (for reviews see Refs. [1][2][3][4][5][6].…”